Once again, it’s the EPA’s turn to sit in the hot seat for rising gasoline prices.

Republicans leading the House Energy and Commerce Committee are taking up that message this week, charging that the agency does little to determine how its regulatory agenda could affect prices at the pump — in particular, with a much-debated plan to require refiners to reduce the amount of sulfur in gasoline.

First up to bat: Rep. Ed Whitfield (R-Ky.), with new legislation that would require a presidential commission to investigate the impact of Environmental Protection Agency regulations on consumer gas prices. A discussion draft of the bill would also clamp down on any new regulations until six months after the commission issues a report to Congress.

“There’s never, at least not recently, been any comprehensive study on what is affecting gasoline prices,” Whitfield said.

Whitfield’s argument is a standard one for Republicans in this Congress: The EPA is pushing out burdensome environmental regulations without adequately examining the true costs for citizens.

And gasoline makes a handy target.

The price per gallon is up a little more than 30 cents from a year ago, according to data from the Energy Information Administration and is rapidly approaching $4 a gallon.

“Every time we go home, we get hit up about gasoline prices,” Whitfield said.

And many of the recent attempts to link EPA regulations to gasoline prices have cast an eye on the agency’s planned sulfur-reduction requirements. (The agency has yet to propose a rule.) Sulfur adds no value to fuel but impairs the effectiveness of vehicle emission control systems, meaning more harmful air emissions. But removing it also means big costs for refiners.

Between 2004 and 2007, refiners met first-time federal requirements to drop the amount of sulfur in gasoline from 300 parts per million to 30 ppm. Now, the EPA wants them to bring it down to 10 ppm.

Refiners say no way.

Environmentalists and state regulators are increasingly impatient that the EPA has not proposed requirements.

Each side has something significant to gain by being right.

Environmentalists want to lower the amount of smog-causing pollution in the air — a danger to public health.

State regulators are already on the hook to find ways to meet a stricter Bush-era ozone standard that’s just now going into effect, after the White House punted on even tighter limits in the fall. But states hope they can meet those limits without any extra work or extra cost — if refiners foot the bill.

On the other hand, petroleum refiners have no interest in being required to implement costly environmental controls.

Most of the rhetoric about the rule surrounds three studies on the cost impacts of lowering sulfur in gasoline — two released by industry and one by environmentalists and state regulators.

In a new study last week, the American Petroleum Institute scaled back the cost and impact estimates for a tightened sulfur limit, saying it could cost refiners an additional 6 cents to 9 cents a gallon to process gasoline.

API previously estimated that the regulation would add between 12 cents and 25 cents a gallon for processing. That figure has often been repeated in Congress and on the campaign trail, although people usually cite it as “25 cents” and often presume that it would be added to the price of gasoline for consumers.

Last week, EPA Administrator Lisa Jackson called that study a “ridiculous price estimate for rules that haven’t even been proposed.”

States, the EPA and environmentalists, on the other hand, say cutting sulfur will cost refiners about a penny on the gallon. Industry says their calculations are flawed.

It is somewhat unclear, however, how much impact refinery regulations could actually have on the price of gasoline.

A recent poll of 37 economists on a University of Chicago panel found that all but three agreed or strongly agreed that changes in U.S. gasoline prices in the past decade were predominantly “due to market factors rather than U.S. federal economic or energy policies.” Those three were “uncertain” — none disagreed with the statement.

The price of gasoline is a function of many market forces, and the price of crude generally has the most impact on the price per gallon, according to the EIA.

In February, the EIA said, about 12 percent of the price of gasoline at the pump was attributed to refining, 11 percent to taxes, 5 percent to distribution and marketing and 72 percent to the price of crude oil.

The percentage of consumer gas prices attributable to refining fluctuates widely every month, according to EIA data from January 2000 to the present, showing a November 2008 low of negative 3.7 percent and an April 2001 high of 32.6 percent. The bulk of the price consumers pay is set by the price the refiners pay for crude oil, according to the EIA.

One expert said the real question at hand for the EPA is whether lowering sulfur will have health benefits to the public that outweigh the cost of the rule to industry.

“EPA’s not denying, of course, and they won’t deny, … that there’s going to be costs” from the regulation, said Michael Livermore, executive director of the Institute for Policy Integrity and adjunct professor at New York University School of Law who focuses on cost-benefit analysis. “The question is whether the costs are justified by the benefits.”

But a clear point, he said, is that the industry study is “not a prediction about gasoline” costs.

“It seems unlikely that they’ll be able to pass on 100 percent of their costs,” Livermore said of the oil companies. “If they can just pass along the costs to consumers, then why fight [the new regulations] tooth and nail?

“It’s not the role of EPA to keep every polluting business in the country open,” Livermore said. “It’s actually businesses’ job to comply with environmental regulations at the cheapest possible cost.”

The House is taking the wrong focus, said Scott Slesinger, legislative director at the Natural Resources Defense Council. “If House Republican leaders were really interested in helping Americans struggling with high gas prices, they’d find ways to give Americans more freedom of choice in transportation,” Slesinger said.

“But instead of supporting fuel efficiency, public transit and other commuting options, they’ve shown once again they’re interested only in supporting their industry supporters and solidifying Big Oil’s monopoly on our transportation system,” Slesinger said.